A known circuit module has a potentiometer that is adjustable from the outside. A tube is inserted before the enclosure with synthetic resin of the axial extension of the operating shaft to provide access to the slotted operating shaft with a screwdriver for adjustment. Thus, this operating shaft remains accessible from the outside. When this tube is enclosed, penetration of synthetic resin into the interior of the tube that blocks access to the operating shaft is frequently unavoidable. A reliable seal between the component and the tube is difficult especially with low-viscosity synthetic resins and foaming. In addition, such an access tube must be protected against clogging by contamination or the like from the outside. Inserting a screwdriver through the thin tube into the slot of the actuating shaft from the adjustable component is likewise difficult and is possible only with a special screwdriver.
There is a need to provide a circuit module having simplified access to the adjustable component's inner actuating shaft, as well as providing contamination protection of the adjustable component and the facilitation of operation of the actuating shaft from the outside.